The effect of several reaction parameters on limonene epoxidation and hydrogen peroxide decomposition over PW-Amberlite was studied. Parameters evaluated were as follows: amount of catalyst (8-28 g/L), average particle diameter (110-720 µm), and concentrations of acetonitrile (7.4-15.7 mol/L), limonene (0.27-1.04 mol/L), hydrogen peroxide (0.73-1.92 mol/L), water (5.84-7.39 mol/L), and limonene epoxide (0-0.17 mol/L). The initial limonene reaction rate exhibits a maximum at 71 wt % acetonitrile (18 wt % hydrogen peroxide), 6.5 times higher than that obtained under biphasic conditions. According to Weisz-Prater criterion, mass transfer limitations were insignificant for catalyst particle sizes smaller than 425 µm. External mass transfer limitations were avoided by using a stirring speed of 1000 rpm. The apparent activation energy of limonene epoxidation was 25 kJ/mol, three times lower than that previously found in a biphasic system. Empirical reaction rates of limonene epoxidation and hydrogen peroxide decomposition are proposed.

In this study, biochar samples acquired as by-product by downdraft gasification at 700 °C from Eucalyptus grandis (BC-EG), Acacia magnium (BC-AM) and Gmelina arborea (BC-GA) were characterized. The morphological characteristics and physicochemical properties of biochar were studied using nitrogen physisorption by the Brunauer-Emmet-Teller (BET) method, Scanning Electron Microscopy (SEM), X-ray Energy Dispersive Spectrometry (EDX) and Fourier Transform Infrared Spectroscopy (FTIR). The surface area (SA) of the materials was in the 2.0-50.0 m 2 /g range, with the biochar obtained from BC-EG showing the highest SA (50.0 m 2 /g), while the biochar derived from BC-GA showed the lowest SA (2.0 m 2 /g). In addition, all samples can be classified as mesoporous materials because their pore sizes were between 2 and 50 nm. This indicates that these materials can be used in absorption processes; however, the biochar obtained from BC-AM is expected to be the most suitable for absorption applications. FTIR biochar spectra did not exhibit characteristic peaks for cellulose or hemicellulose in any sample due to decomposition of these compounds at the gasification temperature. Moreover, according to SEM/EDX analyzes, all the samples presented well-defined pore structure and contained minerals as Na, K and Ca, suggesting that the biochar could also be useful for soil amendment applications.Keywords: Acacia; Biomass charcoal; Eucalyptus; Forestry products; Forestry species; Gmelina; Physicochemical property. ResumenEn este estudio se caracterizaron muestras de biocarbones obtenidos como subproducto del proceso de gasificación, en lecho fijo a 700 °C, de las especies Eucalyptus grandis (BC-EG), Acacia magnium (BC-AM) y Gmelina arborea (BC-GA). Sus características morfológicas y propiedades fisicoquímicas se evaluaron usando * M. Sc. Instituto de la Ciencia y la Tecnología Alimentaria INTAL (Medellín-Antioquia, Colombia). produccioncientifica@intal.org. ** Ph. D. Politécnico Colombiano Jaime Isaza Cadavid (Medellín-Antioquia, Colombia). anardila@elpoli.edu.co. *** Ph.D. Universidad de Antioquia (Medellín-Antioquia, Colombia). rolando.barrera@udea.edu.co. ORCID: 0000-0002-8718-9242. Morphological and physicochemical characterization of biochar produced by gasification of selected forestry species fisisorción de nitrógeno por el método de Brunauer-Emmet-Teller (BET), espectroscopia de dispersión de energía de rayos X (EDS) y espectroscopia infrarroja con Transformada de Fourier (FTIR). Los biocarbones analizados presentaron áreas superficiales en el rango de 2.0-50.0 m 2 /g; el biocarbón originado de la especie BC-EG presentó la mayor área superficial (50.0 m 2 /g), mientras que el biocarbón obtenido de BC-GA mostró la menor (2.0 m 2 /g). Por otro lado, las muestras obtenidas pueden clasificarse como materiales mesoporosos debido a que su tamaño de poro estuvo entre 2 y 50 nm; esto indica que dichos materiales pueden usarse en procesos de absorción, aunque, se espera que el material proveniente de BC-AM sea el más adecuado par...

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A mathematical model for limonene epoxidation over PW-Amberlite in a batch reactor was developed and used for reactor simulation and optimization. The mathematical model was validated by comparison of predicted and experimentally determined limonene conversion under isothermal and nonisothermal conditions (23-50 °C) and for several limonene/oxidant molar ratios. By a sequential simulation and an optimization approach using genetic algorithms (GA), the temperature profiles minimizing the energy consumption and the variability of limonene conversion were obtained. Simulation of limonene epoxidation using the optimal temperature strategies showed that it is possible to achieve a limonene conversion of 80% in a shorter period of batch time when compared to typical isothermal conditions at 33 °C. The proposed model may also be used to scale up the catalytic system. As an illustrative example, an optimization formulation was proposed to estimate the minimum volume (18 L), the aspect ratio (height/diameter, H/D ) 1.7), and the temperature profile that maximizes limonene conversion and minimizes energy consumption to obtain at least 1000 g of limonene epoxide.

The kinetics of limonene epoxidation catalyzed by PW-Amberlite under triphasic conditions is described. A mechanistic pathway was postulated, and a heterogeneous kinetic model was derived following pseudostationary-state theory. Using adsorption parameters that were estimated from independent binary adsorption experiments, the resulting kinetic model fitted the experimental data quite well.

Isobaric liquid-liquid equilibrium (ELL) data (tie lines and miscibility gaps) for the ternary system water + acetonitrile + limonene were determined at atmospheric pressure and at temperatures ranging from (296.15 ( 0.5) K to (323.15 ( 0.5) K. The reliability of the experimental tie-line data was ascertained by using two overall concentrations for each tie line. The equilibrium data were correlated using NRTL and UNIQUAC equations. New and previously unavailable UNIQUAC and NRTL interaction parameters were obtained. Experimental data were also compared with those predicted by the UNIFAC group contribution method. At the studied temperatures, the UNIQUAC equation fit the experimental data better than NTRL, with a root-mean-square deviation value between 0.39 % and 0.99 %. The miscibility gap disappears for an acetonitrile mass fraction equal to about 81 % at 306.15 K.

Chitin is an aminopolysaccharide of industrial interest commonly obtained from shrimp processing waste through chemical or biotechnological means. Current environmental concerns offer a stimulating perspective for chitin bioextraction with lactic acid bacteria since a considerable reduction in the use of corrosive and pollutant products is possible. Nevertheless, the efficiency of this bioprocess is still a matter of discussion. In this work, the experimental studies of chitin bioextraction from Pacific white shrimp (Litopenaeus vannamei) waste with a mixed culture of Lactobacillus plantarum, Lactobacillus bulgaricus and Streptococcus thermophilus are used in process simulation using Aspen Plus software for the analysis of the potential application of a bioprocess on plant scale. The experimental results of characterization in shake flasks and 1-litre bioreactor indicated that 50 h of fermentation with the mixed culture of lactic acid bacteria was enough to extract more than 90 % of minerals and proteins from the shrimp waste. The use of experimental parameters in the simulation allowed a reliable representation of the bioprocess yielding normalized root mean square values below 10 %. Simulation was used for the assessment of the impact of the raw material variability on the production costs and gross margin. In this regard, the gross margin of the operation ranged from 42 to 52 % depending on the raw material composition and product yield

ResumenEn el presente trabajo se desarrolló un modelo en equilibrio que permite simular el proceso de producción de un syngas útil para la obtención de biocombustibles líquidos y/o productos químicos mediante gasificación en lecho arrastrado. El proceso fue modelado mediante el software Aspen Plus, considerando las etapas de pretratamiento y acondicionamiento de la biomasa (secado, torrefacción y molienda), gasificación en lecho arrastrado, limpieza y acondicionamiento del syngas producido, y ajuste de la relación H 2 /CO, adicionalmente se modela la Unidad de Separación de Aire (ASU) para la producción de oxígeno como agente gasificante. La validación del modelo se realizó a partir de datos experimentales reportados en la literatura, mediante el análisis de los errores relativos para las variables de interés: relación H 2 /CO, poder calorífico inferior (LHV, de sus siglas en inglés Lower Heating Value) y eficiencia en frío, obteniendo errores de 7,8%, 11,8% y 8,8%, respectivamente. Adicionalmente, se evaluó la sensibilidad del modelo para predecir el efecto de variables de proceso como la temperatura de torrefacción y la relación equivalente sobre las variables respuesta H 2 /CO y LHV, obteniendo con el modelo tendencias similares a las reportadas en la literatura bajo diferentes condiciones de operación, lo cual muestra que el modelo es sensible a cambios en los parámetros del proceso. Por tanto, se considera que el modelo desarrollado es una herramienta computacional útil para realizar análisis de sensibilidad en procesos de producción de biocombustibles líquidos y/o productos químicos a partir de gasificación de biomasa en lecho arrastrado. Palabras clave: gasificación en lecho arrastrado, Aspen Plus, biocombustibles líquidos, biomasa, syngas.Abstract A model to simulate the entrained flow gasification process to produce a syngas useful in the synthesis of liquid biofuels and/or chemicals was developed. The model is simulated in Aspen Plus and includes the stages of: pretreatment and conditioning of biomass (drying, torrefaction and grinding), entrained flow gasification, cleaning and conditioning of syngas produced, adjustment of H 2 /CO relation, and an Air Separation Unit (ASU) for oxygen production as gasifying agent. The model validation was performed from experimental data reported in the literature, by analyzing the relative errors for the interest variables: H 2 /CO, lower heating value and cold gas efficiency, founding errors of 7.8%, 11.8% and 8.8% respectively. Additionally, the sensibility of the model to predict the effect of process variables as torrefaction temperature and equivalence ratio on response variables, showed similar tendencies to those found Cita: Suárez L, Pérez JF, Barrera R. Gasificación de madera para la obtención de un syngas útil en la producción de biocombustibles y/o productos químicos. rev.ion. 2017;30(1):57-71.